README: Update copr repository in the installation section #168

Job	Run time
check / editor-config	6s
check / clang-checks	1m 37s
build-os-matrix	3s
make-tests (oraclelinux:9) / tests	1m 47s
build (oraclelinux:9) / build	2m 3s
rpm-build (oraclelinux:9) / rpm-build	5m 48s
rpm-install (oraclelinux:9) / rpm-install	1m 14s
	12m 38s

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